With the introduction of distributed energy generation systems, for example private photovoltaic solar power plants, wind turbine plants, hydroelectric power plants and combined heat and power plants, research is being increasingly carried out into integrating electrical energy stores in order to compensate technology-induced chronological fluctuations in the generation of energy by a large number of, in particular renewable, energy sources. A combination of a plurality of optionally distributed electrical energy sources, energy stores and/or energy consumers is often referred to here as a so-called micro grid.
In traditional concepts, different electrical energy sources, energy stores and/or energy consumers are usually integrated separately, with respectively separate power electronics, into one system. Each unit, comprising electrical energy sources, energy stores and/or energy consumers with different properties, requires separate power electronics here, composed of a converter or inverter, in order to adapt the electrical output variables, i.e. the current profile and voltage profile, to a common power grid, for example a common busbar. On the one hand, such systems are very expensive owing to the individually required converters or inverters which are adapted to a maximum power. In addition, they generate increased losses because each converter or inverter has to comply with the common electrical output parameters, for example 230 V AC or three-phase current and at the same time generally large voltage differences have to be bridged. Furthermore, they restrict the freedom of an operational regulator to reach an optimum operating point of the overall system, since common electrical output parameters generate peripheral conditions within which the varying of the operating point must remain, even if an overall optimum of the system were outside these conditions.
In particular, in the case of vehicles, according to traditional electrical drive systems with oscillating motors or three-phase motors, simple converters for generating approximately sinusoidal current profiles or voltage profiles are generally used for an electrical machine. These typically involve current-controlled or voltage-controlled two-point circuits. Current-controlled two-point circuits usually use bipolar components, here thyristors, in order to generate an amplitude for an electric machine by means of a phase angle control. Such circuits are also widespread in large-scale drives, for example in trains. Relatively new vehicles use voltage-controlled circuits virtually exclusively. However, there is generally very high distortion here in respect of current and voltage, which can cause interference in the respective electronic devices and aging of the driving components as well as oscillations and torque ripple. So-called multilevel converters can remedy this. Multilevel converters, for example neutral point clamped (NPC), flying capacitor, modular multilevel converters or MMSPC (Modular Multilevel Converter with Series and Parallel Module Connectivity) can generally generate only one alternating voltage or one three-phase voltage, for example for one or more drives. These supply voltages are generally in the high-voltage range above 60 V, typically above 200 V, and are usually fed from one or more high voltage accumulators. Respective outputs of the multilevel converters are not galvanically disconnected from one another and/or at least not from the at least one high voltage accumulator. However, electrical vehicles, ships, aircraft and the like generally have not only at least one voltage system, usually drive systems, but also further energy supply systems, usually low voltage supply systems. These may be, for example, a lighting system in order to deal with secondary assemblies, controllers or communication devices. For example, in contemporary vehicles there is usually at least one supply system with 12 V, 24 V, and/or 48 V DC voltage. 110 V or 230 V alternating voltage in the form of domestic sockets are also widespread, to a lesser degree.
Furthermore, in addition to multilevel converters, other power electronic systems and also batteries are also increasingly of modular design. However, it is generally not easily possible to expand or replace individual modules owing to hard wiring. In order to replace individual battery modules, for example a network access storage, the corresponding accumulator must be temporarily taken out of operation.
CN 204360204, which is incorporated by reference herein, describes a control unit for limiting the speed for a vehicle. The control unit is composed here of a microcontroller (MCU), connected to various modules, in particular for emergency alarms, steering control, windshield wipers, fog lights etc.
U.S. Pat. No. 7,146,260 B2, which is incorporated by reference herein, discloses a dynamically configurable multiprocessor system.
US 2012/0053754 A1, which is incorporated by reference herein, and WO 2013/052043 A1, which is incorporated by reference herein, disclose a design of an electrical communication and control module for use in a vehicle.
U.S. Pat. No. 8,548,646 B1, which is incorporated by reference herein, describes a distributed hardware architecture for a driverless vehicles.
CN 104267217 A, which is incorporated by reference herein, and CN 204129079 U, which is incorporated by reference herein, describe a design of a hot plug for use in an external area.
The integration of electrical energy sources, energy stores and/or energy consumers which are not of the same type into a single device is known from Selvakumar et al. [S. Selvakumar, P. Kulanthaivel (2014), which is incorporated by reference herein. A new hybrid cascaded h-bridge inverter for photovoltaic-wind energy system. Proceedings of the International Conference on Innovative Trends in Electronics Communication and Applications, 130-140.], which is incorporated by reference herein, Parker et al. [M. A. Parker, L. Ran, S. J. Finney (2013), which is incorporated by reference herein. Distributed control of a fault-tolerant modular multilevel inverter for direct-drive wind turbine grid interfacing. IEEE Transactions on Industrial Electronics, 60(2): 509-522.], which is incorporated by reference herein, Ahmed et al. [N. A. Ahmed, A. K. Al-Othman, M. R. AlRashidi (2011), which is incorporated by reference herein. Development of an efficient utility interactive combined wind/photovoltaic/fuel cell power system with MPPT and DC bus voltage regulation. Electric Power Systems Research, 81:1096-1106.], which is incorporated by reference herein, and US 20020036430, which is incorporated by reference herein, wherein the device itself can act as a converter or inverter. However, these known devices have the deficiency that they can only be expanded with difficulty. Either all the electrical energy sources, energy stores and/or energy consumers must already be connected for the initial putting into operation, or sufficient terminals must already be provided for further electrical energy sources, energy stores and/or energy consumers. Replacement of, for example, defective elements during ongoing operation is not provided here.
A function of a converter within the scope of the present disclosure denotes the capability of replacing energy between at least two connected electrical systems in such a way that different electrical properties of the two systems, composed of a time profile of current strength and voltage, are adapted to one another. For example, the voltage or the current flow is increased, reduced and/or inverted. In addition, adapting the electrical properties can also include a time profile and relate, for example, to conversion of direct voltage to alternating voltage/three-phase current or of alternating voltage/three-phase current to direct voltage. In addition, a converter function can include conversion of alternating voltages with different phase numbers and/or amplitudes and/or different frequency and/or different phase positions.
Inverters are often considered to be a subgroup of the converters which is distinguished by the fact that an alternating voltage is generated in contrast with that electrical system which is connected and which predominantly features as an energy consumer.